A dead-eyed nun in a sexy habit takes the controls of the Hellevator — a simulated elevator ride from, yes, hell. The rickety box jolts and rocks from side to side. While the ride lasts mere minutes, the experience is just shaky enough to scare the free candy out of everyone.

It's only August. But the second annual ScareLA, held in a downtown high-rise design center and showroom called the Reef, is wall-to-wall Halloween. The two-day convention brings in revelers who bleed orange with exhibitors, panels, workshops, films and previews of large- and small-scale haunts, mazes and even Terror Trucks — like haunted houses with four-wheel drive.

Halloween is big bucks in the entertainment capital of the world, and theme parks are a huge part of the revelry. From September to November, Universal Studios' Halloween Horror Nights, Knott's Scary Farm, Queen Mary's Dark Harbor and Six Flags Magic Mountain's Fright Fest transform nearly the entire acreage of the theme parks into freaky spectacles with walkthroughs, live shows and other features designed to make you puke into your funnel cake.

At ScareLA, the creative minds behind the attractions lead panels that draw long lines of fans, eager to learn about this year's additions.

"We wanted to do this far out enough so we don't disturb people's Halloween plans," ScareLA producer David Markland explains. "This is our last opportunity to grab people from Knott's and Universal Studios and places like that before they start putting up their builds. This is also when they start launching their big promotions. We wanted to be the place where they could come and channel their efforts and talk about what they're doing."

Working with a team that includes some 70 volunteers, Markland and executive producer Lora Ivanova drew an impressive 4,000 people to last year's inaugural event. This year, the number grew to 6,000.

For them, the spooky day is a yearlong love affair. For the vendors on site Saturday and Sunday, it's also a business, with products that range from cute (hair accessories, pirate jewelry, vintage decorations) to morbid (dolls and teddy bears with exploded guts) to just plain gross (a scented fog-machine spray that smells like poop).

Planning a wedding? The Cake Countess makes a cake that resembles Leatherface from The Texas Chain Saw Massacre. A séance? For $1,950, Mr. Chicken's Prop Shop sells a "Sybil the Clairvoyant" crystal ball similar to the one in Disneyland's Haunted Mansion. What about a zombie outbreak? Savage Productions has a "zombie killing kit" — goggles, gloves, machete — for just $365.

The convention's four floors are filled with the undead roaming, lurking and — at times — crawling about. Costumed characters mix with equally done-up attendees: scary nurses, scary schoolgirls, scary banjo-playing hillbillies, scary man in bunny mask motioning passersby to sit on his lap (maybe if it was Easter?).

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Bone Yard Effects, run by Universal makeup artist Larry Bones, has one model looking like a serpent and another like a swamp creature, while the Decayed Brigade Slider Show sends monsters dancing and sliding down the exhibitor's space to songs like Poison's "Nothin' but a Good Time."

"People follow every year what mazes are coming out and where in the park they're coming out, down to which stand," he says. "The Knott's characters all have names and trading cards. I thought it was a gimmick, but there's a whole legion of people who collect these cards and know the monsters' names, year in and year out. They know the designers' names the way they would film directors or celebrities. They know everybody who puts this stuff together and at each park."

One of those characters is the Queen Mary's Ringmaster, who looks like a cross between Dr. Frank-N-Furter and Dame Edna. "Excuse my sunglasses," she says greeting the crowd. "I'm not used to being out in a month that doesn't start with the letter O."

Undoubtedly, Knott's has the largest and longest-running haunt. It has run for more than 40 years. This year, the park's team introduces new mazes with names such as the Tooth Fairy (inspired, according to one rep, by a visit to the dentist). When another rep announces the return of the Hanging, a popular live show that spoofs celebrities and pop culture, an audience member asks, "Can you hang Obama in that?"

The event's big surprise is director John Landis, who takes part in Universal's slide-show presentation of the upcoming An American Werewolf in London attraction, which is based on his 1981 horror flick. "You're the best," a fan shouts.

"Oh, my mom is here," the filmmaker shoots back.

Landis discusses penning the script as far back as 1969 and working with makeup effects master Rick Baker, who was then a virtual unknown. Not anymore. "I think Rick has seven Oscars," Landis says. "That little shit."

ScareLA also features some dozen small haunts. There are nearly 100 in the Greater L.A. area, according to Markland and Ivanova — ranging from haunted houses to full-scale productions. Scott D'Avanzo, who's with Mystic Motel in Ladera Ranch, Trevor Nielsen of Perdition Home in Yorba Linda and Jacob Chase, with Big Worm's Sherwood Scare in Northridge, talk about how they terror-fied their private residences using stories, actors and soundtracks. Chase built his set on a basketball court, and D'Avanzo even installed a "dark ride" in his garage.

Budding DIY horror masters hoping to follow in their footsteps take notes in a class taught by Bruce Stanton, who has been staging Reign of Terror in Thousand Oaks for the past 15 years. (Tip: When it comes to fog machines, less is more.) Making costumes out of bedsheets, creating wounds, the "brilliance of black light" — everybody learns something over the weekend.

For Ivanova, 35, Halloween means checking out these home haunts or friends' parties, especially in Burbank, where there are "a lot of amazing backyards." Markland, 42, prefers to go trick-or-treating with friends and their kids. "I even go as far as putting on masks and knocking on doors with them," he says.

Though the two share an affinity for Oct. 31, their backgrounds couldn't be more disparate.

Markland, who lives in Hollywood and runs Halloween blog Creepyla.com, grew up in Ohio and Connecticut. "Seeing Halloween on the shelves was the one thing that brought me out of the depression of having to go back to school every year," he says. "I'd be able to get my friends to go to a cemetery or pull out a Ouija board or tell a spooky story. The rest of the time I just thought I was an oddball."

Ivanova, who also lives in Hollywood, produces and directs theater. Raised in communist Bulgaria, she moved to the United States when she was 21. "I definitely didn't know about Halloween in my early years," she recalls, "but I always had a love for scary movies and playing dress-up. I grew up basically in the capital of puppet theaters. I grew up in a dark room with all these characters floating around, created by people's imaginations.

"A part of me has always remained a child and a believer that we are entitled to our own self-expression," she continues. "That's the spirit of Halloween that I most relate to. At least one day a year, it's OK to be anything and anyone."